Mechatronics Systems Engineering - Theses, Dissertations, and other Required Graduate Degree Essays

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Design and Implementation of Power Drive Controllers for LED Strings

Date created: 
2015-09-01
Abstract: 

In this thesis, design and implementation of power drives for light-emitting diode (LED) strings is investigated. We particularly focus on design methods for minimizing the size of output filter capacitor in flyback LED drivers. To this end, a novel constant power drive technique was developed to achieve better LED light regulation compared with the constant current technique. We present a filter capacitor minimization algorithm and applying it to an integrated buck-boost/flyback LED driver to achieve a long lasting LED driver. Minimization of the filter capacitor in an ac-dc flyback converter is investigated by utilizing a descent algorithm. The algorithm was proposed using a relationship between input current harmonics and LED electrical and photometric characteristics. The performance of the proposed algorithm in terms of filter capacitor minimization was experimentally verified to achieve input power factor correction along with meeting light flicker requirements. Furthermore, a primary-side constant power drive technique is proposed by utilizing a novel LED power estimation technique and an inner-outer-loop control structure. The proposed technique was implemented on an ac-dc flyback converter to attain simultaneous input power factor correction and LED light regulation. The enhanced performance of LED light regulation for the proposed technique is experimentally verified for different ambient temperatures and compared with the constant current drive method. The above filter capacitor minimization algorithm was utilized and experimentally tested in an ac-dc integrated buck-boost/flyback converter. Utilizing this algorithm, the size of the required filter capacitors can be significantly reduced.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Mehrdad Moallem
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

High performance modular insulating panel development for a reefer van

Date created: 
2016-04-04
Abstract: 

A new modular insulation panel technology for insulating reefer vans is proposed that can solve some of the problems of traditional methods. New insulating materials with lower thermal conductivity and aging rate are considered to be sandwiched in composite panels to provide better thermal performance in addition to stronger structure. The developed technology can be applied on a variety of commercial vans to improve the quality of insulation while reducing the cost and installation time of the process dramatically. The present method suggests prefabricating of modular insulation panels with accurate size in controlled conditions instead of spraying insulation foam inside the vehicles. In addition, the installation method of modular panels enables the operators to replace the damaged parts of insulation easily with less cost instead of changing the whole insulation in the old method. The MATLAB optimization toolbox is utilized to optimize the thickness of insulation panels based on energy cost and operational conditions. To validate the proposed model, a full-scale prototype is built and installed on a Ford transit connect and tested under road conditions for performance approval.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Development of Efficient Air Conditioning and Refrigeration System for Service Vehicles

Author: 
Date created: 
2016-03-31
Abstract: 

This research aims to develop a proof-of-concept demonstration of a high efficiency vehicle air conditioning and refrigeration (VACR) system to be employed in service vehicles. The work herein is part of a collaborative research project with two local companies: Cool-It Group, and Saputo Inc., with a main focus on service vehicles. Due to global energy consumption and the environmental impacts of air conditioning and refrigeration (A/C-R) systems, the development of a high efficiency system can significantly contribute to green and sustainable development and environmental protection. This research fills a gap in the literature by developing real-time thermal and performance characteristics of the VACR systems employed in the food transportation industry. Field data is acquired from pilot refrigerated service vehicles during different seasons of the year and the duty cycles are established. The acquisition of field data begins in stationary A/C-R systems and continues in mobile VACR systems. Moreover, a testbed is built in the Laboratory for Alternative Energy Conversion (LAEC) for more comprehensive experiments. Mathematical models are developed for thermal and performance simulations of VACR systems under steady state and transient operating conditions. The models are validated using the laboratory and field data and employed for a thermal and performance investigation of VACR systems. A proof-of-concept demonstration of high efficiency VACR systems is built in LAEC using variable speed compressor and fans and high efficiency heat exchangers. The modeling results are validated and used to develop an optimization model. The optimization model is validated and utilized to determine the optimum compressor and fans speeds for achievement of the highest coefficient of performance (COP) under real-time operating conditions. The optimization model is integrated with an existing cooling demand simulator to develop a proof-of-concept demonstration of a proactive and model predictive controller (MPC) for the VACR system. The controller is implemented on the laboratory-built VACR system and a proof-of-concept demonstration of high efficiency VACR is finalized. The developed concept and platform is expandable to the entire transportation industry as well as stationary A/C-R systems.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Micromachined devices for impedance matching in automotive power line communications

Author: 
Date created: 
2016-04-13
Abstract: 

In power line communication (PLC), the signals are carried and distributed by the wiring system. It is a promising technology which uses the existing system and has wide coverage; however, the impedances at the interface of the power line and the loads are not well defined. The mismatch in the impedances causes potentially high attenuation. This problem can be addressed by developing impedance matching circuit using tunable components based on micro-electromechanical systems (MEMS). In this thesis, the MEMS-based approach was investigated. The tunable inductors and capacitors were designed, fabricated and characterized. A microfabrication process was designed to realize thin membranes attach to the structural layer. The deflection was characterized for a range of actuating voltages. The tunable capacitors were employed in the matching network and tested. The test results were compared with the theoretical results and discussed. This thesis demonstrates the electrostatically actuated MEMS devices and matching network that can work in the PLC system. Furthermore, this thesis should serve as the groundwork for students who wish to design the impedance matching networks or who wish to fabricate electrostatically actuated MEMS devices with thin membranes of their own.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Behraad Bahreyni
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Employing piezojunction effect for resonant micro-device applications

Date created: 
2016-03-03
Abstract: 

This dissertation reports on the application of the piezojunction effect as a new mechanism for measurement of resonance frequency in silicon-based micro-systems. It has been known that mechanical stress can affect the electrical characteristics of diodes, transistors and electronic circuits. This phenomenon is recognized as piezojunction effect. To explore the piezojunction effect as an effective detection mechanism in a micro-device, a micro-resonator structure is designed to employ the inherent mechanical amplification of displacements at resonance as an enabling platform. The proposed structure is capable of mechanically amplifying the sensing signal at the resonance frequency by its quality factor, which can be in the range of tens to hundreds of thousands. This amplified displacement makes the piezojunction effect a practical sensing method for resonator applications. In this technique, the sensing current is stemmed from the dependency of electrical characteristics of an embedded p-n junction to the periodic stress profiles inside the resonating body. The p-n junction is reverse-biased, therefore, due to low sensing current, the required power for detection of resonance is rather small. To employ the piezojunction technique, the author has developed an in-house Silicon-On-Insulator (SOI) micro-machining process to fabricate the proof-of-concept micro-resonator and its embedded p-n junction. Fabricated resonators were packaged and experimentally tested to verify the feasibility of the design and to gauge the performance of the piezojunction mechanism for resonance sensing. The static and dynamic responses of the fabricated devices are experimentally verified. The extensional-mode frequency of the resonator was measured to be 7MHz with a mechanical quality factor of around 5,000. The required power consumption for this sensing mechanism was as low as 5nW. The experimental verifications demonstrate that the piezojunction effect is a promising addition to existing detection techniques in resonance-based applications, where small chip area, integration, and power consumption are key requirements.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Dr. Behraad Bahreyni
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Dissertation) Ph.D.

Multimodality based Tissue Classification Technique for Malignant Anomaly Detection

Date created: 
2014-08-11
Abstract: 

A multi-sensor based tool has been developed to aid physicians performing clinical exams, focusing on cancer applications. Current research envisions improvement in sensor based measurement technologies to differentiate malignant and benign lesions in human subjects. The tool integrates (initially) three different modalities to detect malignant anomalies: electrical impedance spectroscopy, electronic palpation and skin surface thermometry. These methods each exploit different physical phenomena of tumors that aid in the early detection of cancers but individually are limited for accuracy and reliability. The multimodality tool has been tested over phantoms (tissue equivalent material), in vitro animal tissue (for establishing multi-modality tissue relationships; e.g. tissue mechanical, impedance properties etc.), in vivo healthy human tissue (for tissue characterization confirmation) and in vivo malignant human tissue (tested on skin cancer subjects). Additional decision making algorithms have further resulted in a more objective anomaly detection tool. As a long-term goal, the development of a low cost, non-invasive, multimodality tool for clinical examination will be a valuable tool in physicians’ office. This potentially will reduce health care costs by reducing unwanted diagnostic tests by providing more objective screening examination and will be very useful in improving rural health or in developing countries where screening/diagnostic resources are scarce.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Mechanical properties of catalyst coated membranes: A powerful indicator of membrane degradation in fuel cells

Date created: 
2015-12-01
Abstract: 

Mechanical durability of perfluorosulfonic acid (PFSA) ionomer membranes in polymer electrolyte fuel cells (PEFCs) is investigated in this thesis. This work contributes to a systematic characterization of the decay in mechanical properties of membranes and catalyst coated membranes (CCMs) that are subjected to controlled chemical and/or mechanical degradation mechanisms. During field operation of PEFCs, the membrane is subjected to a combination of chemical and mechanical degradation, resulting in the loss of mechanical integrity and ultimately leading to lifetime-limiting mechanical membrane failure. Accelerated stress tests (ASTs) were performed in this study in order to investigate the decay rate caused by each individual degradation mechanism, and to simulate the failure modes of field operated fuel cells. Mechanical degradation was studied using humidity cycling (in-situ) or mechanical fatigue stress (ex-situ). Chemical degradation was evaluated via open circuit voltage (OCV) or elevated voltage (in-situ) or Fenton’s reagents (ex-situ). Moreover, the combined chemical and mechanical degradations were also taken into account following recently developed protocols. In order to investigate the evolutions in mechanical properties during the degradations, different mechanical experiments were utilized including tensile, fatigue, thermal and hygral expansion, and creep tests in a wide range of hygrothermal conditions from the defined room conditions (23°C – 50% RH) to the fuel cell operating conditions (70°C – 90% RH) covering the expected range of operating conditions in PEFCs. Once the mechanical properties of the baseline membrane and CCM were characterized, the effect of each individual degradation mechanism was carefully investigated. Microstructural characterization techniques were also utilized in order to obtain supplementary evidences to the changes in mechanical properties. As a result, chemical degradation was revealed to be the dominant mechanism that controls the decay in mechanical properties of the PFSA membranes and can result in early stage mechanical failure in the presence of mechanical or hygrothermal stress. However, pure mechanical degradation was also recognized to be capable of creating membrane physical damage but at lower rates compared to chemical degradation mechanisms. Slight decay in mechanical properties of the 8,200 hours field operated CCMs was observed, indicating their relatively milder operating conditions when compared to the accelerated stress tests, and further suggesting that the membranes were still in rather good health after this amount of field operation. According to the outputs of this work, critical degradation routes on membrane mechanical stability were diagnosed and mitigation strategies were introduced in order to enhance the membrane mechanical durability and overall fuel cell lifetime.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Erik Kjeang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Metamodel-based Product Family Design Optimization for Plug-In Hybrid Electric Vehicles

Author: 
Date created: 
2015-11-24
Abstract: 

Plug-in Hybrid Electric Vehicles (PHEVs) have been recognized as a solution to mitigate the green-house emission for transportation. A factor to succeed in the marketplace is to provide products that can meet customer expectations and satisfy various functional requirements. As such, the design of PHEVs for diverse market segments requires sufficient differentiation in this product to maximize customer satisfaction with the new technology. However, there are challenges coupled with diversity in production of such a complex product for various customers. This dissertation attempts to address the challenges. This thesis proposed the use of product family design to ensure both the manufacturing efficiency and the customer satisfaction for PHEVs in various market segments. A thorough review of the developments in product family design is first performed, and directions for developing an efficient family design methodology are identified. In order to select the desired or the most preferred variants for the family design purposes, a review of the market studies and fleet data for PHEVs has been performed and summarized as well, based on which a set of five PHEVs- known as variants- are selected for family design assessments. Thirdly, a methodology is proposed for PHEV product family design to enable scale-based design of the selected PHEV variants. The proposed method is verified through a test problem from the literature, and its application to the PHEVs design provides design solutions for the PHEV product family under study. Since the vehicle performance is assessed through expensive simulations, it is shown that the selected optimization algorithm, along with the commonalization strategy and the decision criteria for commonalizing specific design variables make an efficient methodology in terms of the computational costs, and the overall performance of the obtained family solutions. The proposed methodology can also find applications in other product designs that involve expensive simulations and unknown design equations.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Gary Wang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Modeling and characterization of micro-porous layers in fuel cells

Date created: 
2015-12-02
Abstract: 

Modern hydrogen powered polymer electrolyte fuel cells (PEFCs) utilize a micro-porous layer (MPL) consisting of carbon nanoparticles and polytetrafluoroethylene (PTFE) to enhance the transport phenomena of reactants and products adjacent to the active catalyst layers. The use of MPLs in advanced PEFCs has aided manufacturing of higher performing fuel cells with substantially reduced cost. However, the underlying mechanisms are not yet completely understood due to a lack of information about the detailed MPL structure and properties. In the present work, the 3D phase segregated nanostructure of an MPL is revealed for the first time through the development of a customized, non-destructive procedure for monochromatic nano-scale X-ray computed tomography (NXCT) visualization. Utilizing this technique, it is discovered that PTFE is situated in conglomerated regions distributed randomly within connected domains of carbon particles; hence, it is concluded that PTFE acts as a binder for the carbon particles and provides structural support for the MPL. Exposed PTFE surfaces are also observed that will aid the desired hydrophobicity of the material. Additionally, the present approach uniquely enables phase segregated calculation of effective transport properties, as reported herein, which is particularly important for accurate estimation of electrical and thermal conductivity. Additionally, two analytical models are developed for estimation of thermal conductivity and diffusivity of MPL, as a function of structural properties, i.e., porosity and pore size. Based on these models, the pore size distribution and porosity of an MPL with a high diffusivity and thermal conductivity is proposed. Finally, a performance model is developed that is used to study the effects of MPL properties on fuel cell performance. Overall, the new imaging technique and associated findings may contribute to further performance improvements and cost reduction in support of fuel cell commercialization for clean energy applications.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Erik Kjeang
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Energy-smart calculation of thermal loads in mobile and stationary heating, ventilation, air conditioning, and refrigeration systems

Date created: 
2015-11-10
Abstract: 

The energy consumption by heating, ventilation, air conditioning, and refrigeration systems forms a large portion of the total energy usage in buildings. Vehicle fuel consumption and emissions are also significantly affected by air conditioning. Air conditioning is also a critical system for hybrid electric vehicles and electric vehicles as the second most energy consuming system after the electric motor. Proper design and efficient operation of air conditioning systems require accurate calculation of thermal loads as well as appropriate design and selection of the refrigeration cycle. The control logic applied to the system further defines the operational costs associated with the performance of the air conditioning or refrigeration system.The common practice in air conditioning engineering includes a primary calculation of thermal loads. Consecutively, the refrigeration system is selected to provide the required cooling or heating load. An alternate design approach in which the thermal loads are not only calculated as the initial design step but are also calculated in real-time is proposed in this thesis. Modern air conditioning systems are equipped with feedback controllers to allow the system to sustain thermal comfort. The real-time calculation and prediction of the room thermal loads improved by measurements is beneficial for energy-efficient control of air conditioning systems especially in vehicle applications that experience highly dynamic load variations. The calculation procedure can be implemented in a load-based controller to provide advanced intelligence for the system operation. This approach can optimize the system performance for the current as well as future conditions and can also be used as a tool for retrofitting existing systems.The objective of the present research is to establish intelligent real-time thermal load calculation methods that can be used to develop energy-efficient control systems in both stationary and mobile air conditioning and refrigeration applications. The proposed methodology consists of developing a variety of models for law-driven and data-driven calculation of thermal loads in mobile and stationary applications. The proposed models are applicable to heating, air conditioning, and refrigeration applications. The contributions of this study include design recommendations that can result in up to 50% increase in energy efficiency for mobile and stationary air conditioning systems.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.